1. Field of the Invention
The present invention relates to a dual head azimuth alignment mechanism in an autoreverse car audio device, more particularly to a dual head azimuth alignment mechanism in an autoreverse car audio device for adjusting an angle of a head making contact with a tape by switching over an azimuth alignment portion according to operating modes.
2. Description of the Prior Art
Audio devices recently developed are designed to accomplish various functions like autoreverse, a section repetition, and etc. Especially, the autoreverse function is to automatically switch a traveling direction of a tape from forward to reverse direction and from reverse to forward direction. Hence, the autoreverse type car audio device needs a tape running direction changeover mechanism for automatically switching the traveling direction of the tape. The autoreverse type car audio also requires an azimuth adjusting apparatus for matching a gap angle of a head (hereinafter, referred to as an azimuth) and an angle between channels on the tape. The reason is that, in the car audio permitting the changeover of the tape traveling direction in either one of the two directions, it is desirable that the head is brought into contact with the tape at an appropriate angle without any regard in which direction of the tape is caused to run. However, it is difficult to adjust the azimuth in the autoreverse type car audio which allows the traveling direction of the tape to change in either one of two directions. Also, when the azimuth fails to be adjusted, a gap between the channel and the head substantially increases. As a result, the cross talk between nearby channels arises from the misaligned position of the azimuth, and the high band of the recorded information is attenuated. To solve the above problems, various apparatus for aligning the azimuth are proposed to adjust a channel aligning angle and the gap angle of the head.
One of the conventional apparatus for aligning the azimuth is described in U.S. Pat. No. 4,809,108. In the conventional azimuth alignment mechanism, on both sides of a magnetic head 20 azimuth alignment screw support members 21L, 21R are arranged. The support members 21L, 21R are rotatably provided about their corresponding pivots 22L, 22R. Both pivots 22L, 22R are provided upright on a plate-like member 23 which supports the magnetic head 20 thereon and is movable back and forth as shown in FIG. 2.
The left-hand and right-hand support members 21L, 21R are provided with projections 24L, 24R respectively as shown in FIG. 3. These projections 24L, 24R are maintained in engagement with their corresponding bent portions 25L, 25R in a bifurcated shape and formed at left and right end portions of the pinch roller changeover member 13. In the respective azimuth alignment screw support members 21L, 21R, azimuth alignment screws 26La, 26Lb; 26Ra, 26Rb are received in front and rear pairs.
In contrast, a mounting base 27 made of a synthetic resin is provided on the upper surface of a plate-like member 23. Guide projections 28L, 28R are provided upright on left and right end portions of the upper surface of the mounting base 27. Above the upper surface of the mounting base 27, a downward-arched leaf spring 29 and a magnetic head support strip 30 are successively arranged. The magnetic head 20 is secured centrally on the support strip 30. The leaf spring 29 and support strip 30 define guide holes 32L, 32R; 33L, 33R through left and right end portions thereof. The guide holes 32L, 32R; 33L, 33R are fit on their corresponding guide projections 28L, 28R, whereby the leaf spring 29 and support strip 30 are movable up and down. Further, upwardly-arched portions 34L, 34R are formed at both left and right end portions of the support strip 30 respectively.
In the state shown in FIG. 1 in which the pinch roller changeover member 13 is turned clockwise, the left hand member 21L turns to the front direction whereas the right-hand member 21R turns rearward. Hence, the rear azimuth alignment screw 26Lb is in contact at bottom thereof with the arched portion 34L on the left, and the front azimuth alignment screw 26Ra is in contact at the bottom thereof with the arched portion 34R on the right. The vertical position and inclination of the magnetic head 20 are controlled by these two screws 26Lb, 26Ra. When the pinch roller changeover member 13 is turned counter-clockwise due to the failure of azimuth alignment, the left-hand member 21L is turned rearward whereas the right-hand member 21R is turned to the front direction. As a result, the front azimuth alignment screw 26La is in contact at the bottom thereof with the arched portion 34L on the left, and the rear azimuth alignment screw 26Rb is in contact at the bottom thereof with the arched portion 34R on the right. The vertical position and inclination of the magnetic head 20 are controlled by these two screws 26La, 26Rb.
Owing to the adoption of the above described structure, the vertical position and inclination of the magnetic head 20 are controlled by the azimuth alignment screws 26Lb, 26Ra when a tape is caused to run in the left. When the tape is caused to run in the right, on the other hand, the vertical position and inclination of the magnetic head 20 are controlled by the azimuth alignment screws 26La, 26Rb.
However, the conventional azimuth alignment apparatus has problems. First, it is hard to adjust the head angle by controlling each pair of alignment screws 26La, 26Rb; 26Lb, 26Ra screwed at the left and right members installed at both sides of the head. Hence, the cross-talk due to interference between the adjacent channels on the tape can occur. Second, it is hard to ensure the stability of operation because the upwardly arched portions 34L, 34R are worn away owing to the frequent contact with the alignment screws 26La, 26Rb; 26Lb, 26Ra for control the head angle respectively. Third, the conventional alignment apparatus has a high manufacturing cost and is complicated because of the complexity of the construction members.